From 6dc404d433adf09045565054aecf85714db95b46 Mon Sep 17 00:00:00 2001
From: Haoqin Huang <haoqinhuang@tencent.com>
Date: Tue, 4 Aug 2026 17:38:38 +0800
Subject: [PATCH] zram: reject zero-size dictionary

kernel_read_file_from_path() already rejects empty files (i_size <= 0) and
returns -EINVAL, but the current implementation only checks for sz < 0
without logging any information.  Use sz == 0 to reject the zero-size case
and print distinct error messages for each failure type.

Link: https://lore.kernel.org/20260804093841.67920-3-haoqinhuang7@gmail.com
Signed-off-by: Haoqin Huang <haoqinhuang@tencent.com>
Signed-off-by: Rongwei Wang <zigiwang@tencent.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Tested-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/block/zram/zram_drv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cfa98846ac48..f73e30b61067 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1700,8 +1700,16 @@ static int comp_params_store(struct zram *zram, u32 prio, s32 level,
 						INT_MAX,
 						NULL,
 						READING_POLICY);
-		if (sz < 0)
+		if (sz < 0) {
+			pr_err("failed to load dictionary %s (err=%zd)\n",
+			       dict_path, sz);
+			return sz;
+		}
+		if (sz == 0) {
+			pr_err("failed to load dictionary %s (empty file)\n",
+			       dict_path);
 			return -EINVAL;
+		}
 	}
 
 	zram->params[prio].dict_sz = sz;